Interview question

How do you work with databases using ORM in web frameworks? Web frameworks में ORM से database के साथ कैसे काम करते हैं?

Answer

# Django ORM
from django.db import models
from django.utils import timezone

class User(models.Model):
    username = models.CharField(max_length=100, unique=True)
    email = models.EmailField(unique=True)
    is_active = models.BooleanField(default=True)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)
    
    def __str__(self):
        return self.username

class Post(models.Model):
    title = models.CharField(max_length=200)
    content = models.TextField()
    author = models.ForeignKey(User, on_delete=models.CASCADE, related_name='posts')
    created_at = models.DateTimeField(auto_now_add=True)
    
    def __str__(self):
        return self.title

# Using Django ORM
from .models import User, Post

# Create
user = User.objects.create(username='john', email='john@example.com')

# Read
user = User.objects.get(id=1)
users = User.objects.all()
users = User.objects.filter(is_active=True)

# Update
user.email = 'newemail@example.com'
user.save()

# Delete
user.delete()

# Relationships
post = Post.objects.create(title='My Post', content='Content', author=user)
posts = user.posts.all()

# QuerySet operations
users = User.objects.filter(is_active=True).order_by('-created_at')
count = User.objects.filter(is_active=True).count()

# SQLAlchemy with Flask
from flask_sqlalchemy import SQLAlchemy

db = SQLAlchemy()
app = Flask(__name__)
db.init_app(app)

class User(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(100), unique=True)
    email = db.Column(db.String(100), unique=True)

# Using SQLAlchemy
user = User(username='john', email='john@example.com')
db.session.add(user)
db.session.commit()

user = User.query.filter_by(username='john').first()
users = User.query.all()
user.delete()
db.session.commit()

Django ORM:
User.objects.create(username='john')
User.objects.get(id=1)
User.objects.filter(is_active=True)
User.objects.all()
user.save()
user.delete()

SQLAlchemy:
db.session.add(user)
db.session.commit()
User.query.all()
User.query.filter_by(id=1).first()

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